Modem speed

Hi,
I have a peculiar problem. I had my modem running very fast on linux since
long and till the other day. Then I re-installed rh6.2 and now the modem
is running really slow. i don't know what the problem is. it gives me
extremely low (too low to mention here) d/l speeds...
I have done the following:
run modemtool and selected the port
put the nameserver entry in the /etc/resolv.conf
entered the neccesary details in netcfg to connect via ppp
it connects fine
after connection it barely gives me any speed
the same modem on the same line in working perfectly in windows
is there something i am missing?
--
Siddharth Kaza
kaza@xxxxxxxx